Heat records in jeopardy as season's first 90-degree readings expected in Northwest
Summer heat will envelop the Pacific Northwest beginning this weekend, with Portland and Seattle among the cities that can challenge or break record highs.
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Mother Nature is about to turn up the thermostat in the Pacific Northwest, with record high temperatures in the forecast for a few days beginning this weekend, say AccuWeather meteorologists.
For some areas away from the coast and in valleys, it will be the first time venturing into the 90s this year, while many other communities will make it into the 80s, well above historical averages for early June.
"Those with outdoor plans this weekend will want to schedule their activities in the morning or evenings to avoid the peak heating hours during the day," AccuWeather Senior Meteorologist Dan Pydynowski said. "If you must be outside, drink plenty of water and take as many breaks in the shade and indoors in air conditioning as possible."

The sun sets over the University District in Seattle, May 13, 2023, seen from 520 Bridge View Park in Medina, Wash., during a heat wave. (AP Photo/ Lindsey Wasson, File)
The increase in temperature will be driven by a building area of high pressure across the West, replacing an area of low pressure which led to locally heavy showers and thunderstorms this week, especially across the Southwest and Rockies.
After rather typical early-June days temperature-wise through Wednesday, the warmth will begin to ratchet up through Friday before records begin to be challenged on Saturday.
"The first 90-degree readings of the year thus far are expected in Portland, Oregon, this weekend," said Pydynowski. "Both Saturday and Sunday's forecast high temperatures will challenge or even break daily records."

The record high temperature in Portland on Saturday of 93 from 1948 may be safe, but it appears the daily record of 94 from 1955 on Sunday is in jeopardy of tumbling, with AccuWeather forecasters expecting a high temperature well into the mid-90s.
Typically, Portland experiences its first 90-degree reading of the year in mid- to late June, so the intrusion of warmth expected this weekend is a couple of weeks ahead of the historical average. "The historical average first date for 95-degree heat in Portland is July 21," pointed out AccuWeather Senior Meteorologist Chad Merrill.

Seattle, while not expected to venture into the 90s, will not be exempt from the warmth. High temperatures well into the 80s are on tap for Sunday and Monday, with Sunday's forecast high close to the daily record of 87 set a decade ago.
Smaller towns east of the Cascades will also be roasting beginning this weekend.

"Spokane, Washington, will flirt with daily records Saturday, Sunday and Monday with highs in the lower 90s expected," added Pydynowski. "Meanwhile, Omak, Washington, will challenge a long-standing record by next Monday, as the high tops out near 99, which is a mark that has stood for over 100 years, since 1918."
While heat waves of this magnitude are not unusual in the Pacific Northwest, especially during midsummer, they can be impactful and potentially deadly.
Only 53 percent of buildings in Washington state have air conditioning equipment, the second-lowest percentage in the U.S. behind Alaska, according to data from the Haas School of Business at the University of California in Berkeley. In Oregon, only about three-quarters of buildings have such cooling capabilities.

"In the wake of a deadly heat wave in June 2021, a study by the National Weather Service indicated homes without air conditioning were warmest between 9 p.m. and 11 p.m.," said Merrill. "For those without air conditioning, staying at a friend’s or relative’s home with air conditioning overnights this weekend is advised."
For those looking for a reprieve from the early-season heat, it is forecast to fade by the middle of next week, as the area of high pressure moves east. Temperatures will return to more typical readings in the 60s and 70s.
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